1. Field of the Invention
The present invention relates to a display device (hereinafter, also referred to as an input device) provided with a display portion having an input function and a method for manufacturing the input device.
2. Description of the Related Art
Display panels to which text information can be input by touching a screen with a finger or a stylus pen have spread and have been used for a portable information terminal such as a PDA (personal digital assistant or personal data assistance), a potable game machine, a car navigation system, and an automated teller machine (ATM), for example.
As such a display panel, a display panel having a screen provided with an optical sensor is known (see Patent Documents 1 to 3). The amount of light received by an optical sensor is changed when a screen is touched with a finger or the like. Accordingly, by detecting the change, the position of the screen touched with the finger can be detected.
In Patent Document 1 (Japanese Published Patent Application No. 2002-287900), a pixel functioning as a display portion and an input portion is provided with an EL element and a photoelectric conversion element. By reflecting light by the point of a pen used for input, accurate information input can be realized.
In Patent Document 2 (Japanese Published Patent Application No. 2006-317682), by controlling on and off of a backlight at the time of image display and optical sensor output, detection accuracy of the optical sensor is improved.
In Patent Document 3 (Japanese Published Patent Application No. 2002-33823), an optical sensor is provided in a pixel of a liquid crystal display device so that an image sensor is incorporated in a screen of the display device, whereby a personal authentication system is constructed.